Presentation on theme: "Chapter 5 Operational Amplifier. Introduction A typical op amp: a) pin configuration, b) circuit symbol An op amp is an active circuit element designed."— Presentation transcript:
Chapter 5 Operational Amplifier
Introduction A typical op amp: a) pin configuration, b) circuit symbol An op amp is an active circuit element designed to perform mathematical operation of addition, subtraction, multiplication, division, differentiation, and integration.
Terminal Voltage and Currents Vd=V2-V1 (differencial input) Vo=AVd=A(V2-V1) A: gain (open-loop voltage gain)
Actual op amp: Ri(very large); Ro(very small); A(very large) Idealization: Ri=> ; Ro=>0 ; A=> As Vo is limited, we can get from Vo=A(V2-V1) that: V2=V1 As Ri=> , we can get i 1 =0, i 2 =0 i1i1 i2i2
Ideal op amp 1)i1=0, i2=0 ; 2)V1=V2 Ideal op amp model i1 i2
Applications Inverting Amplifier
Applications Noninverting amplifier If Rf=0; R1= , then=>
The voltage follower ViVi VoVo First stage Second stage Applications
Difference Amplifier Note: be careful while using nodal analysis, do not set nodal equation at the output terminal.
Example: Find out Vo
P.P.5.10As a voltage follower, v a = v 1 = 2V where v a is the voltage at the right end of the 20 k resistor. As an inverter, v b = Where v b is the voltage at the right end of the 50k resistor. As a summer v 0 = = [6 - 15] = 9V